<html>
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">On 27-Feb-16 14:19, Bob Supnik wrote:<br>
</div>
<blockquote cite="mid:56D1F6C8.6040105@supnik.org" type="cite">Thanks,
Tim. Burroughs made a lot of fixed head disks at the time. I can't
identify the model, but the IA2 (see page 7-4 of the B6700
Hardware Handbook, on bitsavers) seems like a possibility. It has
7552 sectors per surface vs 8000, but Burroughs sectors were
longer than DEC sectors (180 x 8b = 1440b vs 32 x 36b = 1152b), so
perhaps DEC format had more sectors per track.
<br>
<br>
While the 18b- and 36b-groups used the same disk buyout, they went
to different vendors for drums. The Type 24 and RM09 came from
Vermont Research; the RM10B from Bryant.
<br>
<br>
/Bob
<br>
<br>
On 2/27/2016 12:00 PM, <a class="moz-txt-link-abbreviated" href="mailto:simh-request@trailing-edge.com">simh-request@trailing-edge.com</a> wrote:
<br>
<blockquote type="cite">Message: 3
<br>
Date: Sat, 27 Feb 2016 09:31:59 -0500
<br>
From: Timothe Litt<a class="moz-txt-link-rfc2396E" href="mailto:litt@ieee.org"><litt@ieee.org></a>
<br>
<a class="moz-txt-link-abbreviated" href="mailto:To:simh@trailing-edge.com">To:simh@trailing-edge.com</a>
<br>
Subject: Re: [Simh] RB09 == RD10
<br>
Message-ID:<a class="moz-txt-link-rfc2396E" href="mailto:56D1B35F.3040206@ieee.org"><56D1B35F.3040206@ieee.org></a>
<br>
Content-Type: text/plain; charset="utf-8"
<br>
<br>
On 27-Feb-16 08:23, Bob Supnik wrote:
<br>
<blockquote type="cite">>Max Burnet gave me a pointer from
some old price lists, showing that
<br>
>the RD10 had very similar specs to the RB09. The RC10
manual confirms
<br>
>it - same BCD addressing of tracks and sectors, same
number of tracks,
<br>
>same sectors per track, same words per sector (32 x 36b
for the RD10,
<br>
>64 x 18b for the RB09). So the "RD10s" on some PDP-9s in
the services
<br>
>listing are actually RB09s, at least at the drive level.
<br>
>
<br>
>I still don't know what an RC09 is. Alternate name for an
RB09?
<br>
>Half-sized variant? Another mystery is who made the actual
drive
<br>
>mechanism. It precedes DEC's first internally designed
fixed head
<br>
>disk, the RF09/RS09, by two years.
<br>
</blockquote>
According to the option module list, the RC09 is a "Control for
<br>
Burroughs Disk" The design engineer was J. Milton.
<br>
<br>
That makes sense, as the RC10 was the PDP10 controller for disk
and drums.
<br>
<br>
FWIW, Family members: the RD10 was made by Burroughs. The RM10B
drum
<br>
was by Bryant. SW documentation was removed from the PDP-10 doc
set in
<br>
the 80s, but as I wrote previously, I believe the tech manuals
are on
<br>
the FS microfiche. The section with the red stripes on top.
<br>
<br>
The drums were notoriously unreliable. Especially the ones in
the Mill,
<br>
though things improved when someone realized that they tended to
crash
<br>
when semitrailers bumped into the loading dock above them....
<br>
</blockquote>
<br>
</blockquote>
I think this is confusing due to the hierarchy/bundling. It's not
complicated,<br>
I think :-)<br>
<br>
Summary:<br>
<br>
RB09 = RC09 + RD10. (-A for 50 HZ) <br>
Probably salable part number.<br>
<br>
RC09 = Controller <br>
Probably not salable, except perhaps as FS spare.<br>
<br>
RD10 = Drive<br>
Probably not salable, ditto<br>
<br>
FS probably used the controller on the contract rather than the
bundle. They did that<br>
a lot. Remember that these early drives each had a dedicated
controller. Later (e.g. Massbus<br>
disks), they'd be listed separately. Or the first drive +
controller had a part number,<br>
add-on drives would be listed separately. But in this timeframe,
which they picked<br>
was arbitrary. <br>
<br>
FWIW, in this case, the FS list indicates that the RC09 shipped much
later than the rest<br>
of the system. The system shipped in july 65; the RC09 in jan 69.<br>
<br>
One other bit of trivia from the OML - the RB/RC09 went status 6 in
July of 71. (6 = Obsolete, but<br>
can still be built.) "TPL" = "traditional products line"; I think
they were in Salem NH at that time.<br>
<br>
Supporting data:<br>
<br>
The (1974) OML edition that I have lists the RB/RC09 & RD10.
The 'C' would indicate controller<br>
(thanks to Dick Best's semantic part number scheme.) I would
guess that RB decodes to<br>
"Rotating magnetic memory", Burroughs" :-) The coding got more
creative as time went<br>
on as the "good" letters were used by early products. (E.g. RK for
"Rotating Kartridge disk")<br>
<br>
There is also an entry for the RB09 and RB09-A - listed as "RC09
& RD10" and "RC09 & RD10-A" <br>
The -A are 50 Hz versions. <br>
<br>
There are RC controllers for the 7, 9, 10 & 11. (The RC11
references the RS64 "65K 16 bit DEC DISK".)<br>
<br>
<br>
<img src="cid:part1.02030705.02020602@ieee.org" alt=""><br>
<br>
<br>
<img src="cid:part2.05050909.05000206@ieee.org" alt=""><br>
<br>
</body>
</html>